Bulk solids that are stored in a container, lie on a conveyor belt or sit on a waste heap usually have an irregular, uneven surface. In particular, the bulk solid can form into a cone or an extraction funnel can be formed.
In this situation, level indicators are often inaccurate in determining the level, in particular if they only measure the distance to a single point on the surface of the bulk material. In order to be able to determine the level with greater accuracy, it can be advantageous to use information about the surface topology of the bulk material.
The surface topology of a bulk material can be detected using a radar level indicator by changing the main beam direction of the antenna. By successive changes to the main beam direction it is possible to take measurements of the surface of a medium from different angular directions or from different positions. The detected echo curves can be used in the measuring instrument or in a suitable analysis unit to determine the surface topology.
The necessary change in the main beam direction can be performed mechanically by swivelling or displacing the antenna. It is also possible to provide an antenna array that detects echo curves from different spatial directions.
DE 101 06 176 A1 describes a level indicator having an adjustable detector head.
DE 689 10 784 T2 describes an antenna having an electronically controlled deflection system.